1. Field of the Invention
The invention generally relates to optical communications with wavelength division-multiplexing, and more particularly, to an optical measuring system and the method for obtaining physical characteristics of light flux emitted from a waveguide array.
2. Description of the Related Art
The wavelength division multiplexing (WDM), as a newly advanced communication technique, transfers an optical signal budget in which various informational contained in light spectrums of plural wavelengths, enhancing a transmission speed (or a data rate) in proportion to the applicable number of wavelengths. Such a WDM needs a multi-channel arrayed light source capable of signalizing information data with light of different wavelengths.
There have been used several kinds of parallel (or arrayed) waveguides, such as variable optical attenuators and optical fiber arrays. The waveguide array is formed of plural waveguides spaced with the same intervals from each other and designed to emit uniform pattern and characteristics of light flux (or beam) from each waveguide. However, it may vary substantially beam patterns and intervals because of manufacturing errors and so on, which downs product yields as well as deteriorating efficiencies of optical coupling and characteristics of optical signals in fabricating arrayed optical device modules with quite precise operations. Therefore, it is important for an improvement of module fabrication process and a management of product quality to accurately measure characteristics of beam emitted from the waveguide array.
Usually is a typical device for measuring the parallel beams to survey beam intervals, uniformities, quantities, and so on, moving each stage on the two-dimensional plane of X and Y axes, when the beams are emitted from waveguides with the maximum power rate after receiving beams through the waveguides, which are arranged with uniform intervals, from a light source. But, it would also result in variations of measurement influenced from accuracy of stages as well as aberrations of lenses accepting the beams from the waveguides.
Even recent high-resolution stages with the order of nanometers are incapable of extending their movement ranges over several hundreds micrometers. On the other hand, enlarging the movement range of the stage inevitably causes the resolution to be lower, accompanying with additional apparatuses such as laser interferometers. A measurement system employing a laser interferometer or a high-resolution stage is less available because it is very expensive and needs environmental cleanness over a predetermined level, further with disadvantages of large bulk and definite endurance.